1. Field of the Invention
The present invention relates generally to writing instruments, and more particularly to a slide-type writing instrument with a dry prevention unit, which is constructed so that a nib which dispenses ink supplied from a cartridge is projected out only when the writing instrument is in use, and the nib is retracted into a body of the writing instrument to be sealed in the body when the writing instrument is not in use.
2. Description of the Related Art
Generally, writing instruments are typically classified into fixed-type writing instruments, rotary-type writing instruments, knock-type writing instruments, and slide-type writing instruments. The fixed-type writing instruments are designed so that a cartridge is fixed in a shaft and a cap is used to cover a nib. The rotary-type writing instruments are designed so that a part of a shaft rotates to make a part of a cartridge be projected out. The knock-type writing instruments are designed so that a cartridge is projected out by a spring when a part of a shaft is pressed. Further, the slide-type writing instruments are designed so that a cartridge slides to be retracted into and projected out of a shaft.
The slide-type writing instruments have an advantage in that it is unnecessary to open or close an additional cap. However, the slide-type writing instruments have a problem in that a nib hole is formed on an end of the writing instrument, so that such a slide-type structure may be limitedly applied to only non-volatile writing instruments, such as oil-based ink.
Thus, writing instruments having high volatility, for example, a marker pen, a correction pen, a roller ball pen, a highlight pen, etc., must have caps, although it is inconvenient to open or close the caps. The reason why the writing instruments having high volatility have the caps is that ink of the nibs is dried up when the nibs of the writing instruments are exposed to the air, thus shortening the life spans of the writing instruments.
In order to solve the problems, there have been efforts to develop a writing instrument which prevents ink of the writing instrument using liquid or semi-liquid ink, or volatile or non-volatile ink from being dried up, while protecting a nib of the writing instrument.
In Japanese Patent No. 1987-0012570, there is proposed a writing instrument titled ‘capless writing instrument with dry prevention unit’. The writing instrument disclosed in the document has a slide-type structure, and prevents a nib from being dried up while protecting the nib. When a user presses a push-button of the writing instrument once, a cover is opened to open a nib hole by a tensile force of an elastic cord. Further, when the user presses the push-button once more, the cover is closed, thus preventing ink from being dried up.
However, the writing instrument according to Japanese Patent No. 1987-0012570 has problems in that it uses the tensile force of the elastic cord, so that the opening or closing of the cover is not rapidly executed, and it has low durability, and further, a sealing effect of the cover to temporarily close a nib hole is very poor.
Furthermore, there is a proposed writing instrument in Korean U.M. Registration No. 172486, registered in 1999 and titled ‘slide-type writing instrument with a tip protective unit’. According to Korean U.M. Registration No. 172486, the writing instrument is provided with the tip protective unit to prevent a nib from being dried up. In this case, the tip protective unit seals the tip of the nib while the products are transported and marketed, thus preventing ink from being dried up.
However, the writing instrument according to Korean U.M. Registration No. 172486 has a problem in that the tip protective unit must be discarded during the use of the writing instrument, so that the writing instrument loses a dry prevention function. Further, the writing instrument may be limitedly applied to a ball-point pen.
Furthermore from Korean U.M. Registration No. 174279, which was registered in 1999, there is a known nib dry prevention unit. According to Korean U.M. Registration No. 174279, when a push-button of a slide-type writing instrument is pressed, the nib passes through a cut slit of a rubber packing to be exposed to the atmosphere, so that a user can write with the writing instrument. Meanwhile, when the push-button is released or is pressed once more, the nib returns to an original position thereof, and the cut slit is closed by elasticity of the rubber packing, thus preventing ink from being dried up.
However, the writing instrument according to Korean U.M. Registration No. 174279 has a problem in that plastic deformation of the cut slit may occur due to frequent use of the writing instrument. The writing instrument has another problem in that it is difficult to seal the push-button, which executes a sliding motion, so that sealing efficiency is low.
In Korean Patent Application No. 10-2000-65693 there is a proposed ‘writing instrument with inseparable elastic cap’. According to Korean Patent Appln. No. 10-2000-65693, the writing instrument is provided with an elastic cap. The elastic cap has, at a predetermined position thereof, a cut slit through which a nib passes. Further, a predetermined portion of the elastic cap, which is opposite to the cut slit, is in close contact with a guide groove of the writing instrument. Thus, when the cap moves backward, the nib is exposed to an outside so that a user writes with the instrument. Conversely, when the cap moves forward, the cap prevents the drying of ink. A middle portion of the writing instrument has the same shape as a body of a usual writing instrument.
However, the writing instrument according to Korean Patent Appln. No. 10-2000-65693 has a problem in that a portion around the cut slit may be stained with ink, because the nib is exposed to the outside through the cut slit. Further, since the cut slit is closed by a subsidiary unit, such as a rubber ring which may be easily elastically deformed, the nib is in direct contact with the cut slit and thereby is broken or damaged, and durability of the writing instrument is relatively low. The writing instrument is problematic in that the rubber ring is exposed to the outside of the cut slit, so that the rubber ring may be damaged when the rubber ring is in contact with an external object. Further, the cut slit may, be deformed due to frequent use of the writing instrument, so that efficiency of sealing the nib may be deteriorated.